I learned something tonight, something that I previously "knew"
but apparently did not "understand." The lesson was delivered
after scratching my head for way too long over the following
seemingly straightforward problem (which I had made the mistake of
assigning before solving) from the current edition of a well known
intro text. I thought others might enjoy the challenge as well.
Here's the problem (what's the lesson?):
In the arrangement shown in the figure, a potential difference V
is applied, and C1 is adjusted so that the voltmeter between
points b and d reads zero. This "balance" occurs when C1 = 4.00
microF. If C3 = 9.00 microF and C4 = 12.0 microF, calculate the
value of C2.